A couple of points.

With regard to footnote 1.

1 Attribution and sources for an item datum overides that for a character or taxon, which override that for the treatment as a whole. Attribution for characters and taxa are equivalent and additive.

Don't we also need to say that item data attribution at the specimen level may override that for a character or taxon as a whole? Otherwise, the system has no way of dealing with misidentifications, particularly if some but not all parts have been associated with the wrong ID, as might be frequently encountered in fossils, or when dealing with taxa whose character state definitions are later found applicable for only a specific size range (ie differentially break down at small sizes). Specimen or parts level data/attributions also would presumably be additive, even if potentially contradictory (subject to differences of opinion), would they not?

This seems a reasonable point .

If we are to presume nested levels of groupings of descriptor elements, then we need to be able to clearly distinguish data values that are regarded as referring to "individual units" (specimen, species, higher level taxon) at one level, but are "collective" when evaluated at a different level. Not only with the "collation rules" be different for different levels, but may be different depending on whether a given feature (possibly "same feature but defined differently") is regarded as a data item refering to a specific "individual unit", or as a "collective unit". That is, the data item is a representation of data that might apply to a collection, rather than a measurable value that may have a scope no larger than a specific measure of a specific specimen. Perhaps some treatments might include "collections of collections" that would imply a mixing of both situations.

I presume you mean Specimen with ID - set of individual measurement or set of measurements (say in mm.) all associated with this specimen (maybe at a particular institution).

Specimens of species: grouped, a larger series of measurements, and/or variously processed (e.g. mean + s.d.)

the measurement(s) of either the specimen or the species could be assigned to states; those states might encompass a range of variation such that the attributuion of a specimen/species to that state would mean that, when refering to the state, one loses sight of the original measurements.

P.